The present disclosure relates to a display unit having a self-emitting type light-emitting element including an organic layer, and an electronic apparatus that includes such a display unit.
In recent years, for a display unit as an alternative to a liquid crystal display, an organic EL display unit has been put into practical use that utilizes a self-emitting type organic EL (Electro Luminescence) element including an organic layer. The organic EL display unit has a wider angle of viewing field as an advantage of a self-emitting type in comparison with a liquid crystal display, and the like, as well as satisfactory response to high-resolution high-speed video signals.
In the past, for an organic EL element, an attempt on improvement of a display performance has been made in such a manner that a resonator structure is adopted, and light which is generated on a light-emitting layer is controlled by enhancing the color purity of luminescent colors or by increasing the luminous efficiency (for example, see International Publication No. WO 01/39554). For example, in a top emission method (top surface emission method) that takes light out of a surface on the side opposite to a substrate (top surface), an anode electrode, an organic layer, and a cathode electrode are laminated in this order via a driving transistor on the substrate, and then multiple reflection of light from the organic layer is carried out between the anode electrode and the cathode electrode.
In an organic EL display unit employing such a top emission method, to assure a high aperture ratio, a cathode electrode located at a sealing panel side is served as an integrated electrode layer that is provided in common on each organic EL element. Further, the cathode electrode is composed of an optically transparent conductive material such as ITO (Indium Tin Oxide) to take light out of a top surface. However, such an optically transparent conductive material exhibits a resistivity greater by approximately two to three orders of magnitude as compared with a typical metallic material, and the like. As a result, it is likely that a voltage that is applied to the cathode electrode may become uneven in plane, and thus a disadvantage has been found that the emission luminance could vary among each of organic EL elements depending on in-plane positions, which makes it difficult to achieve a satisfactory display quality.
Consequently, to resolve such a disadvantage, an organic EL display unit has been proposed that forms an auxiliary wiring to be connected with a cathode electrode on the same layer on which, for example, an anode electrode located at a driving panel side is formed, thereby suppressing voltage drop of the cathode electrode in an in-plane direction (for example, see Japanese Unexamined Patent Application Publication No. 2010-244808). In such an organic EL display unit, for example, the auxiliary wiring is connected with the cathode electrode at an area out of a display region of each organic EL element. In such a manner, above-described variation in the emission luminance among each of the organic EL elements depending on in-plane positions is alleviated to some extent by laying out the auxiliary wiring in a mesh form along the cathode electrode extending in an in-plane direction and by connecting the auxiliary wiring with the cathode electrode.